Individuals in many health related professions, e.g. medicine, pharmacy and biology, frequently have a need to prepare standard solutions of buffers, possibly in the presence of metal ions; or to calculate certain solution parameters from other known quantities. These calculations are often rough approximations, since a complete model of even simple aqueous buffer solutions may require the use of iterative numerical techniques in order to solve dissociation, complex formation and solid phase equilibria, concurrently with the determination of activity coefficients. For basic science applications, it may be necessary to fit parameters to equilibrium data, to link with a differential equation solver for kinetics simulations, or to calculate solubility isotherms and phase diagrams. This project will develop software tools for these sorts of problems, and enable health science researchers to formulate and evaluate complicated solution equilibrium models in a timely and precise manner. The software will allow users to specify solution properties such as pH, buffer capacity, etc; then equilibrium reactions will be automatically retrieved from an internal database, mass balance relationships will be transparently constructed with a built in "equilibrium compiler", and a variety of output may be calculated. This software will be designed using rigorous software design and project management techniques, and will utilize the experience of scientists who together have many years of experience in solving complex chemical equilibrium problems.